How to disable safety mode in Youtube?

I mistakenly turned safety mode on in Youtube, to see what it would do. Now I can’t turn it off. When I try and turn it off, it gives me the error message:

“Safety Mode is locked by __FZzNZ_txKN__
Safety Mode Lock prevents others from changing the Safety Mode setting on this browser. You must sign out and sign in as __FZzNZ_txKN__ to unlock.”

I don’t have a Youtube account with that user name. I don’t understand who this __FZzNZ_txKN__ person is. No one else uses my laptop besides me so I know no one else has created an account.

How do I fix this? This is preventing me from watching alot of videos that aren’t inappropriate at all.